1. Field of the Invention
The present invention relates to a method of non-linear display of routes of at least one of a machine-tool and another mechanism and which includes determining a set path based on stored commands and determining an actual path based on actual displacements during operation of the at least one of a machine-tool and another mechanism resulting from execution of the stored commands, graphically displaying the set path and components of the actual path, which extend parallel to the set path, at a first scale, and graphically displaying components of the actual path, which extend perpendicular to the set path, at a second scale.
2. Description of the Prior Art
Japanese Publication JP-A-07072914 discloses a method of displaying a return route of a tool with which a workpiece is machined. In order for the operator to be able to simultaneously recognize the displacement speed, the type, color and width of the line, which represents the route, change dependent on the displacement speed. At the points of the route, at which the tool speed is above or below a predetermined value, an attention mark is displayed.
The method of the Japanese Publication JP-A-07072914 does not provide for display of deviations of the actual path from the set path.
Japanese Publication JP-A-58-158713 discloses a method of automatic calculation of a scale and of a position of a tool and a workpiece profile and displaying the information on a display device associated with a numerically controlled machining equipment. The processing information, which is displayed by the display device, occupies the entire available display surface of the display device. The processing information can include a tool route and the machined profile of a workpiece.
However, the display does not permit the operator to compare the tool route with the machined profile of the workpiece. Therefore, the deviations of one line from another are not readily recognizable.
U.S. Pat. No. 5,315,523 discloses a display device of a numerical control unit which displays both the workpiece and the tool. In order to insure an optimal use of the display surface of the display device at all times, a new scale is calculated each time the distance between the tool and the workpiece changes. Thereby, it is insured that both the tool and the workpiece are always shown at a scale which permits to recognize the most possible number of different details.
However, the display of set and actual paths is not contemplated. A further drawback of this display device consists in that at a large distance between the tool and the workpiece, the workpiece in particular is displayed as a very small element. Therefore, an immediate recognition of an erroneous route is not possible.
European Publication EP 510 204 A1 discloses a method of determining the accuracy of a numerically controlled machining equipment. First, a numerical control command is fed to a control of a machine-tool. After execution of the command, the tool route is fed from the machine-tool to the control unit, and the deviation of the actual tool route from that prescribed by the control command is determined. In this way, the accuracy of the machining equipment is determined. Both the set path, which is determined by the control command, and the actual path, which is fed to the control unit, are graphically displayed on the display device. The operator has a possibility to determine the display scales in the X- and Y-direction dependent on the displayed deviations of one path from another.
The drawback of the method, which is disclosed in this European Publication, consists in that the scale can only be changed for the entire display device and not for selected regions of the graphical display. Thus, a selection of an enlargement, which permits to recognize the deviations between the set and actual paths, would not permit a complete display of the entire workpiece.
International Application W094/07187 discloses a method of testing the machining accuracy of a numerically controlled (NC) machine. The NC-machine has at least two axes each having its own drive which is controlled by a servo control loop. The NC-machine further includes a linear encoder for each axis. In accordance with the method, a circular set path is produced by the NC-machine, and a circular actual path, which is obtained based on the NC-machine movement, is compared with the circular set path. For comparison by the operator, both the set path and the actual path are graphically displayed.
One of the drawbacks of this method consists in that, the deviations of the circular actual path from the circular set path are so small at the contemporary NC-machines that the deviations cannot be recognized when the entire circles are displayed by the display device. With an enlarged display of only one section of the circle, the operator cannot see at which point of the circular path the largest error is observed. Further, with a complicated route, a circle does not permit the operator to clearly recognize which portion of the route is straight.
International application WO 97/27521 discloses a method of determining and optimizing the machining accuracy of a machine-tool or a robot. A course of a set path, which is determined by a sub-program available in the numerical control, is compared with an actual path. For determining the actual path, position measuring systems, which are available in a machine-tool for at least two axes, are used. for displaying the profile deviation, the geometrical relationship between the set and actual path is evaluated. The difference between the set point vector and the associated actual point vector is displayed in a direction perpendicular to the course of the set path.
The drawback of the method disclosed in this international application consists in that the entire route cannot be shown when the sectional enlargement takes place in order to make the deviations of the actual path from the set path more recognizable. The display of the entire workpiece is, thus, not possible.
Accordingly, an object of the present invention is to provide a method with which both the entire route display on the available display surface is possible, and the deviations of the actual path from the set path can be qualitatively assessed by the operator.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a method in which at a selected points of the set path, the set path and the components of the actual path, which extend parallel to the set path, are displayed at a third scale, and at the selected points of the set path, the components of the actual path, which extend perpendicular to the set path, are graphically displayed at a fourth scale.
The advantage of the method according to the present invention consists in that the sections of the route, in which no large deviation of the actual path from the set path is expected or takes place, are shown at a reduced scale, and the sections of the route, in which large deviations of the actual path from the set path are expected or take place, are shown at an increased scale. By selecting different scales for a single display, the sections of the route, which are of most interest to the operator, are displayed in detail, without a loss of the possibility of displaying the entire route.
The present invention, thus, provides for a user-friendly display of the set and actual paths. Because the operator can rapidly recognize the deviations, a possibility is created for displaying the entire route in a window of the display device, in addition to the enlarged display of the important sections of the route. Despite the display of the entire route, even small deviations of the actual path from the set path can be shown in detail. This is achieved by changing the scale at critical points such as, e.g., at corners of the set path or at points where a large deviation of the actual path from the set path takes place. Changing of the scale, as discussed above, permits to show the relevant sections of the set and actual path at an increased scale.
In addition, the displacement speed can be displayed in such a manner that the line representing the set displacement speed coincides with the set path, and the actual displacement speed is either determined in absolute terms and is superimposed onto the set displacement speed or is determined as a percentage of the set displacement speed likewise superimposed onto the set displacement speed. This makes immediately clear at which point of the set path the deviation of the speed from the set value takes place.